The present invention relates to a resin-sealed semiconductor device.
A resin-sealed semiconductor device is a device having a semiconductor chip (IC) package made of molding resin. The resin-sealed semiconductor device is inexpensive and excels in mass-productivity. Therefore, it is most generally developed and manufactured in the field of semiconductor devices.
FIG. 1 is a plan view of a conventional resin-sealed semiconductor device. FIG. 2 is a sectional view, taken along line II--II in FIG. 1. FIG. 3 is a sectional view, taken along line III--III in FIG. 1.
A semiconductor chip 11 is mounted on a die-pad 10. The chip 11 is secured to the die-pad 10 with electrically conductive adhesive 12 such as silver paste. Tie-bars 17 tie the die-pad 10 to a lead frame in the course of manufacturing a resin-sealed semiconductor device. A plurality of leads 13 are arranged around the die-pad 10. Bonding wires 14 connect the leads 13 to the electrodes (pads) 15 of the semiconductor chip 11. Resin 16 covers the semiconductor chip 11. Those parts of the leads 13, which are in the resin 16, are called inner leads. Those parts of the leads 13, which are outside the resin 16, are called outer leads.
The die-pad 10, leads 13 and tie-bars 17 are made of metal such as copper, copper alloy or iron-nickel alloy (Fe--42Ni). The distal portion (bonding portion) of each lead (inner lead) 13 is plated with metal such as gold or tin. The bonding wires 14 are made of metal such as copper, copper alloy or gold. The electrodes 15 of the semiconductor chip 11 are made of metal such as aluminum.
The leads (outer leads) 13 are made in the form of a Gull-wing so as to easily contact the wires provided on a printed circuit board. The tie-bars 17 is used to tie the die-pad 10 to the lead frame in the course of manufacturing the resin-sealed semiconductor device. Those parts of the tie-bars, which are outside the resin 16, are therefore finally removed. Hence, the tie-bars 17 will exists in the resin 16 only.
The die-pad 10 is fixed at the ground potential in order to stabilize the operation of the integrated circuit provided within the semiconductor chip 11. A method of fixing the die-pad 10 at the ground potential is known, in which one of the leads 13 and the die-pad 10 are connected to each other and the ground potential is applied to this lead 13.
In this case, however, the ground potential is applied from the lead 13 to the die-pad 10. Due to the resistance components of the leads, bonding wires and die-pad, it is difficult to stabilize the entire lower surface of the semiconductor chip 11 at the ground potential.
Further, since one of the leads 13 must be used to set the die-pad 10 at a specific potential, the semiconductor device needs to have more pins (outer leads) than otherwise. Still further, since the lead (outer leads) are bent in Gull-wing form, there is limit to miniaturization and thickness reduction of the semiconductor device.